Thin-Gap Single-Pass High-Conversion Reactor for Organic Electrosynthesis II. Application to the Anodic Methoxylation of 4-Methoxytoluene

The four-electron anodic methoxylation of 4-methoxytoluene has been performed in a thin-gap, single-pass, high-conversion reactor at ambient temperature and pressure, with an inlet reagent concentration of 0.1 M, methanol solvent and coreactant, 0.01 M KF supporting electrolyte, and current densities up to 240 A m−2. Product selectivities greater than 90% have been obtained for reagent conversions greater than 95%, corresponding to very high product yields in a simple single-pass technology. The generated volumetric hydrogen flux is 3-7 times higher than the volumetric liquid flux, resulting in a substantial decrease of the electrical conductivity in the 100 µm wide interelectrode gap. Nevertheless, the experimental results compare very well to reactor simulations performed with the electrochemical cell model developed in Part I of this study [J. Electrochem. Soc. 155, E193 (2008).] Adjustment of a single parameter, the value of the average mass-transfer coefficient, is sufficient to fit the simulations to the experimental results, and the results suggest that the electrochemical reactor model developed should be of use for application to other electrochemical reaction systems also.